


You think some feeble light can save you from the darkness?

by SoftButchCassidy, TheBookwormBakery



Series: Destiny Hearts Crossover [1]
Category: Destiny (Video Games), Kingdom Hearts
Genre: Canon-Typical Violence, Hive Corruption, Mind Control, dawnblade sora, defender riku, happy (mostly) ending, nightstalker kairi, sora voice i'm going to save you with the power of friendship and this gun i found
Language: English
Status: Completed
Published: 2020-01-10
Updated: 2020-01-10
Packaged: 2021-02-27 03:20:15
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,052
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22200184
Author URL: https://archiveofourown.org/users/SoftButchCassidy/pseuds/SoftButchCassidy, https://archiveofourown.org/users/TheBookwormBakery/pseuds/TheBookwormBakery
Summary: They've been searching for Riku for so long, they'd nearly lost hope. Then there was the brief flicker of it, a spark of hope-- now snuffed out by the shadows that consumed their beloved Defender, that cloaked the once noble Titan, that possessed their friend's Light. They have one chance to tear the dark from him.
Series: Destiny Hearts Crossover [1]
Series URL: https://archiveofourown.org/series/1598011
Comments: 1
Kudos: 10





	You think some feeble light can save you from the darkness?

**Author's Note:**

> me n my gf have been working on this au for months lol enjoy!!  
> her ao3 is TheBookwormBakery

Sora stared at the gate. His fingers tightened on his gun. 

“Um… so… knock knock?”

Kairi almost laughed. Sora saw her shoulders twitch a little bit. It was more than she’d done in a while, since Riku had gone missing. “I don’t think it works that way.”

“How do we…”

Kairi grabbed his arm, but he was already stepping back. 

“Sora--”

“Whoa.”

The ground shook as the portal in front of them flickered. A sickening green light swirled into life. The air itself thrummed with a dark energy. 

“How did it open?” Kairi whispered. 

“I don’t know,” Sora replied. “Um… we should go in, though! Riku’s in there!”

“I don’t like that it just… opened.”

“No, I don’t either. But we have to save Riku before Xehanort can… can… I don’t even know what he’s planning on doing! Or--” 

Both Guardians jumped at a dull roar behind them. They whirled to see glittering green eyes stalking from the shadows.

“Or before the Hive find us,” Sora finished. He stepped backwards, toward the portal. “Kairi, c’mon, quick!”

“But what if--”

The ground shook again, and a hulking figure loomed out of the dark.

“Okay, never mind! Riku!” 

They darted for the portal. 

It wasn’t the first time Sora had gone through a portal to the Ascendant Realm. A wave of what could be nausea rolled over him, a blast of something like being plunged into ice cold water, the cloying feeling of death. 

His only comforts were Kairi’s void-chill touch on his arm, the warm assurance of his Ghost, and the burning need to find his lost fireteam member, his best friend. 

“Oh, I don’t like it here,” Kairi’s voice murmured. 

Sora blinked open his optics. 

The colors were washed out, nearly gone, a blue-black echo of reality. It looked… Sora didn’t know how to think of it. It wasn’t like Oryx’s, or Crota’s. It was like an island, or many islands, floating in the void of the Sea of Screams. A sourceless wind howled, tugging at his robes, at Kairi’s cloak. 

“Where do we go?” Kairi asked over the wind.

“Um… Dawn?” Sora said.

A shimmer accompanied the manifestation of a Ghost beside Sora. The Ghost’s shell twitched as it looked into the abyss. “He’s here,” Dawn said, voice soft. “I can feel him.”

Sora readied his rifle. “Alright. Let’s go find him and bring him home.”

Kairi’s fingers tapped nervously at the trigger guard of her sidearm. “I’m with you, Sora.”

Dawn vanished again and the two Guardians slowly began to make their way forward across the dusty stone. 

It was quiet. 

So when gravel crunched, they froze.

Something let out a low, deep growl.

They whirled around.

A Titan stood behind them. His armor was dented, scratched. His fingers twitched on the handle of the jagged-edged blade in his hand. 

Sora couldn’t lift his gun, even when he could see the black smoke curling off the Titan’s armor. 

Kairi’s breath hitched. “Oh, Light… Riku?”

The Titan jerked their head. Slowly, they reached their hand up. They scraped their fingers at their helmet, and tugged it off.

Riku’s eyes were solid, glittering green. 

Sora couldn’t breathe with the well of horror in his chassis. 

Riku curled his lip. A guttural snarl rolled from between his teeth and he took a lurching step forward.

“Riku,” Kairi said quickly, panicked, clutching her gun tight. “Riku, no, please, wait, we’re--we’re here to save you, to help you! We--”

Riku bared his teeth. The end of the sword slammed into the ground. 

He lifted his hand.

Sora braced himself.

Riku… pointed.

Behind them?

Sora turned in confusion. There didn’t seem to be anything. The only thing on his display was the blinking red marker on the radar where Riku stood. 

Sora looked back at him and reached out his hand. “Riku, c’mon, before the portal closes again, we can get you back to the Tower, and--”

Whatever growled noise Riku made sounded almost frustrated. He tightened his hand on the sword and shifted his weight. 

Sora knew that stance.

Riku lunged.

Kairi ducked with a gasp. Her form flickered and vanished. Sora barely managed to skip back from the jagged blade. 

“Riku, no! Stop!” Sora pleaded. “I don’t want to do this!”

Riku dragged the blade across the stone and hefted it again. 

“Please!” Sora tried. Terror filled him. 

He couldn’t lose hope, Riku was here, right here in front of him, after so long, he had to save him, stop whatever this was--

Riku swung the sword again. 

Sora had to leap back from it. He stumbled on the gravel at the edge of the platform and barely caught himself from tumbling into the void below. “Riku!”

Riku stared silently at Sora for a long moment. He took a slow step forward. 

He reached out.

Hope lifted in Sora’s chest. He held out his hand toward Riku. 

“Sora!” Kairi yelled.

Riku snapped his head toward her as she reappeared. Then his unsettling eyes landed back on Sora and he pounced forward.

The world seemed to slow down as Riku tackled Sora off the edge. 

It was a dizzying, terrifying flashback to leaping into the entrance to the Hellmouth, to Crota’s throne world, as they spun into the abyss. Darkness screamed in Sora’s head.

Riku was clinging to Sora’s armor with one hand, the other gripping the sword tightly. Riku’s mouth twitched and he growled something out.

“Riku! What?!” Sora tried to ask. The words were torn from his mouth.

Riku grabbed his collar and leaned close. The voice that came out of his throat wasn’t Riku’s. “Fly.”

With that, Riku let go, and plummeted.

Sora tried to catch him. He hadn’t realized he’d let his glide activate. He tensed himself and free-fell down into nothingness.

Something crashed with a loud crack beneath him. 

Sora waited, and then gasped sharply. He touched the Light to glide again, just in time to stop himself from slamming into a platform he couldn’t have seen from so far up above. 

He landed on light feet and looked up. 

Riku stood staring at him again. 

“Riku, what’s going on? What happened to you?” Sora asked. “Did he do this to you?”

Riku shuddered violently and turned his face. He bared his teeth, shook his head, growled wordlessly. Sora was… beyond unsettled. 

“Let me help you,” Sora begged.

Riku’s chest heaved with a sharp breath in. He tightened his hand on the sword.

“No, no, no, Riku, stop, stop, no!”

Sora barely dodged out of the way again. Flames curled along his fingers, but he stayed his hand. He couldn’t do that, even if Riku was… was… whatever this was. 

Taken? No. No, he couldn’t be Taken. Riku was a Guardian.

_ What was this? _

Riku attacked again. Sora could feel the air rush past him, the edge of the sword brush against his shields.

Something else was wrong.

Riku was putting all his strength into every swing, but… he hadn’t hit yet. Riku didn’t miss. 

“Riku?” Sora asked. 

Riku paused, just for a moment. His head angled to the side.

Something pink shot past. Kairi gasped and stopped her free-fall with a small hop in midair. “Sora!” she yelled. 

Riku glanced toward her before looking back at Sora. 

Sora was almost easily able to duck out of the way this time. 

“Wait, Kairi!” Sora called as Kairi lifted her sidearm. “He’s not hitting me!”

Riku’s mouth twisted into something like a grin. 

“He’s--what?”

Sora backstepped the next swing. “He’s missed every time! He’s… not trying to hit me!”

Kairi’s hand shook. She couldn’t aim it at him. “Riku…?”

Riku said something, but it wasn’t English. Sora got a horrible feeling about what it was. 

“Are you trying to lead us somewhere?” Sora asked. Time for charades?

Riku lunged again, forcing Sora backwards. 

“Oh, Riku,” Kairi murmured. She ran forward after them. “Okay. I guess we’ll dance.”

Riku nearly seemed to… laugh. 

Sora couldn’t turn his back on Riku, so he was careful to look over his shoulder before dodging. Every slam of the sword into the ground made him flinch. It was an awful sound, ringing in his ears. Kairi kept pace, worry clear on every movement she made.

It was… it was… hard was an understatement. Sora was reeling. His best friend stared him down with unblinking eyes as solid and bright as any bloodthirsty Knight, bared his teeth and swung the brutal stone edge of a sword at him. He backstepped through the Ascendant Realm, hoping to the Traveler that Riku wasn’t leading them into a trap. 

Another question jolted Sora. How did Xehanort’s throne world get this big? 

How many people had he killed?

Sora didn’t think he wanted to know the answer to that question. 

Walls rose up around them, tall pillars, vaguely Hive-like in their architecture. Sora slowed as Riku did. They stood in a triangle in some kind of large, round room… thing. 

Riku breathed heavy from the exertion. He leaned on the sword and stared them both down. 

“What’s going on, Riku?” Sora implored. “Please, please let us help you. We’ve been looking everywhere to find you!”

Riku shuddered again, worse than before. He doubled over and retched. 

“Riku?” Kairi asked in alarm.

Blood dripped from Riku’s lips. He panted hard for breath that rasped between his bared teeth as he leaned over the sword, shaking. The black mist nearly billowed from his armor now.

Slowly, Riku straightened. He took a step forward, then another. The sword dragged against the stone with an awful sound. 

He staggered, paused to spit blood on the ground, and struggled on. 

He passed Sora and Kairi to the other side of the room. He clutched his chest and coughed, a wet, sick sound. Smoke leaked from his eyes, poured down his face, reminding Sora of Eris with a jolt of fearful pain. 

Riku rasped something in that unholy tongue and gripped the sword tightly. He took a deep breath and looked up.

There, above them, in the center of the room, floated a violet crystal. 

Sora stared at it. Hive crystals usually were… significant. What did Riku want them to do with this one? 

Kairi lifted her sidearm and fired off a shot before Sora could even react.

The bullet pinged harmlessly off the crystal.

Riku shuddered and grunted in pain, grabbing at his chest again. They were connected?

“Do we need to destroy that?” Sora asked.

Riku’s teeth were stained red. He tried to speak again. 

The walls rumbled. 

Riku staggered and grabbed at his head now. His fingers tightened in his hair, and he grunted in pain. Sora started to step forward, a panicked exclamation in his throat. 

Eyes glittered in the shadows, green and white alike. 

“Sora,” Kairi hissed. Her hand reached for his, and he gripped her fingers tight. She was cold. “What do we--”

“We save him,” Sora said. He stared at Riku even as the Thrall stalked out of the shadows. “I promise, Riku.”

Riku dropped his hand. It didn’t shake anymore as he grasped the sword. 

The Hive swarmed. Taken followed. 

Kairi stepped back with void curling around her fingertips. “I’ve got a tether,” she said. Her voice cracked.

Flames licked off Sora’s armor as he fired at the Hive. Riku stayed still, staring silent. “Okay,” he said. “We’ll figure this out, I know we will.”

Kairi swallowed and leapt up. She kicked off the air once more and pulled back on her bow. Gravity warped in her palms and she aimed for the crowd of Thrall. The arrow plunged into the stone with a deep boom and the hungry tethers lashed out from the black hole it opened. 

Sora let the fire wash over him. Grenades flew from his hands, scorching through the Hive, burning the Taken into mist. How did Xehanort get Taken? They were mostly Hive and Vex, Sora noted, irritation seeping in as he waited for two Goblins to stop shielding each other. 

The tether held the Hive still as Sora’s Light torched them into ash. Riku still wasn’t moving. Why? What was he waiting on? 

A dull roar rattled the walls. 

Sora grabbed Kairi to keep her steady. They both looked up in alarm as a hulking figure loomed from the shadow. The Knight twitched and seethed with Taken energy, its lone white eye glowing. 

“That… looks bad,” Sora said. 

Kairi holstered her sidearm and readied her fusion rifle. Its end glowed with void. 

Four bolts of hungry void burst out of it. The Knight roared and stumbled back as the bolts exploded. 

Sora looked past the Knight and froze.

Where did Riku go?

The Knight seethed into nothingness.

Pain exploded in Sora’s back. His shields cracked at some massive blow, and he stumbled forward with a yelp of pain. 

Blindly, he whirled and fired. 

Riku hadn’t missed that time. 

Sora had to focus just on dodging him now. Riku wasn’t trying to miss anymore. 

“Stop! Riku, please!” Kairi cried out over the howls of the Hive and the Taken. 

This time, Riku didn’t react. He just lunged again, moving robotically, viciously. It wasn’t the way Riku moved, it was… strange, unfamiliar. Sora struggled to match it.

A snarl announced the arrival of another Taken Knight. 

“I’ll get it!” Kairi yelled. 

Riku stopped. Just for a second, he froze.

He twitched and whirled on Kairi. 

Kairi shrieked and backstepped away from the Knight. She flickered into shadow, cloaked by her Light. 

Riku stood close to the Knight as it stalked forward. He was shuddering again, bleeding again. 

The Knight lifted its sword and brought it down into the ground. Green light washed out from the blade, curling in magic flames in a ritual circle. Sora backed up. 

The fire spread out, then up the walls.

The crystal overhead began to glow. 

Riku staggered and cried out in pain as the crystal’s light grew brighter. The Hive and the Taken backed away with hisses and snarls.

“What is--” Sora started.

The green fire was taken over by violet. It looked nearly like one of the Voidwall grenades that Kairi, that void Hunters, used.

Defenders used them, too.

The Knight roared as the purple flame washed over it. Riku doubled over. His sword clattered to the ground as he clawed at his armor, all but writhing in clear agony. 

The Knight wrenched its sword from the ritual circle and turned to face Sora and Kairi. Its white eye had turned deep purple. Void purple. 

“That’s Light,” Sora’s Ghost whispered in horror. “It… it’s using Light.”

Riku cried out and fell to his knees as the Knight stormed forward. 

Sora and Kairi had no choice but to flee. They bolted away from the Knight’s slash, behind it. But they couldn’t leave Riku behind, they couldn’t, and Sora wouldn’t. 

The Knight roared and gave chase. 

“That’s Riku’s Light!”

Sora fired at the Knight. “What?!”

He could hear the panic in Dawn’s voice. “I can-- I can feel it! That’s Riku’s Light, oh, Traveler, what did they do?”

Sora shot the Knight and it staggered back.

Riku yelled wordlessly and snapped his head around. “No!”

Sora’s optics widened. 

Riku shuddered in pain. “N… no,” he rasped.

The Knight raised its sword. 

Cold hands met Sora’s armor. He stumbled to the side as he was shoved.

He looked up as Kairi crumpled under the Knight’s blow. 

Sora scrambled back with a sharp gasp. “Kairi!”

A shimmer peeked out of Kairi’s cloak. Her Ghost was too scared to revive her yet, with the Knight looming over her body. 

Sora tightened his jaw and stood up as the Knight turned to look at him. 

He raised his rifle… and aimed up.

The Knight charged as he pulled the trigger.

Crystal shards rained down.

The Knight froze.

Riku froze.

Sora staggered back from the unholy scream that the Knight made. The violet light--the Light--that had fueled it grew so bright, Sora could feel it. It writhed as Riku’s stolen Light tore its body apart. 

Riku flung the sword away and stumbled upright. The purple fire flickered out around the room. 

“Riku!” Dawn exclaimed.

Riku looked up at Sora, grasping his chest. He was still in bad shape… his eyes still glowed green, and that Taken mist leaked from his armor. “Sora,” Riku rasped. 

Sora took a step toward him. 

Riku shook his head and gestured weakly at Kairi’s body. He tightened his fists and looked at the Hive creeping forward.

Sora ducked down to funnel his Light into Destiny’s shell. Kairi gasped for breath. She accepted Sora’s offered hand to haul her to her feet. “Riku! Are you okay?” she asked.

“We gotta go!” Sora said. “Riku, can you…”

“I… know the… way out,” Riku managed to get out. “Just… kill, first.”

Sora held out a hand cannon to him.

Riku gave him an echo of a smile and raised his gun. 

It felt good to fight side by side again. 

“I’m going to tether again!” Kairi exclaimed after a minute or so. “Get ready!”

Sora let fire flicker over his armor. 

Kairi pounced up to draw back her bow, and unleashed the arrow on the Hive again. 

They gunned down the Hive, working as a team again. Sora could have laughed with elation when Riku charged forward with his shield and crashed it into a Knight.

The burst of joy seeing his friend use the Light again faded to worry when Riku staggered back with a gasp of pain. 

“Are you--” Sora started.

Riku shook his head. “Don’t… worry about me,” he said. His voice sounded hoarse. “S’fine.”

“But--”

Riku huffed and lifted his cannon at the Taken. 

Sora shared a worried glance with Kairi. 

They nearly got through the last of them unfazed. 

Sora turned around to grin at Riku, to say something to him, but what came out instead was a warning yelp.

Riku didn’t have time to dodge the Knight. 

It didn’t have time to dodge Kairi. 

Both crumpled to the ground.

“Oh, no!” Kairi landed beside Riku. “Sora, where’s Dawn?”

Sora shot a few more Acolytes before hurrying over. He held out his hand to let them appear. They zoomed forward for their Guardian. 

Dawn stared down at him. Their shell split apart and rotated around their core. “Riku…? I… Kairi, help me?”

Kairi reached forward. Sora felt the burst of Light.

Nothing happened. 

“Dawn, what’s happening?” Kairi asked, alarmed.

“I… I… I don’t know.” They sounded scared. “I can bring him back, I know I can, he’s here, but… there’s so much Darkness…”

Sora flung out his hand to scorch a Thrall. “Let’s get somewhere safe! Let’s get him out of here!”

“How? Only he knows how to leave!” Kairi said.

“Uh…”

“Get him away from the Hive!” Dawn exclaimed. “I can bring him back, but it’s hard! I need a minute!”

Sora slid along the ground and looped his arms under Riku’s. He grunted as he hauled his friend into his arms. He started to drag him backwards. 

Kairi kept shooting the Hive, glancing worried over her shoulder. 

He finally hauled Riku out of the room, back into the howling wind of the Ascendant Plane. He set him down and stood protectively over him. 

Dawn split apart their shell and pulsated with Light. 

Seconds ticked by. Sora felt fear trickle cold into his chest.

Finally, finally, Riku gasped for air, his eyes flying open. They were still terrifyingly green, but no longer solid. He staggered upright, catching Sora’s hand for balance.

“Riku! Are you okay?” Sora asked.

Riku coughed. “Yeah… yeah, I’ll be okay,” he rasped, voice hoarse. “Let’s just get the hell out of here before he comes back.”

“How?”

Riku narrowed his eyes. “Follow me.”

They darted after him as he ran for the edge of the cliff. He leapt off, and his Light pushed him forward. Sora had never been so relieved to hear a Titan’s jets. 

There were narrow platforms here, floating precariously in space. Riku seemed to know exactly where they were. Sora and Kairi couldn’t see them until they got close; they had to trust Riku, and they did.

The Hive’s roars faded into the distance. 

“Where are we going?” Kairi yelled over the wind.

“We’re getting away from his throne world,” Riku called back. “Just stay behind me, and don’t go anywhere else!”

The world seemed to get darker as they moved farther away, the wind louder. Sora had no idea how long they were navigating the platforms. 

Eventually, Riku took a longer leap forward. He landed with a small stumble on a slightly larger chunk of rock. “Over here! Careful!”

Sora landed easily beside him, and they both reached out to catch Kairi. 

Riku tightened his jaw and turned around. He held out his hand and traced symbols with his fingers. He mumbled something.

Sora frowned and stepped closer. 

Riku was muttering in the Hive language.

Riku’s eyes flashed, and he moved like he was grasping the air in front of him. With a grunt, he pulled, and ripped open a seam in reality. 

Sora stared at him with his eyes wide.

Riku sagged with exhaustion. “It won’t stay open long,” he said. “C’mon, let’s get out of here.”

“How did you--” Sora started.

“I’ll explain later! I don’t know if I can do it again without killing myself.” Riku grabbed their arms. “Please, I want to go home.”

Sora knit their fingers together. They stepped into the portal.

The air screamed in Sora’s ears, and the only thing that kept him grounded were his hands gripping Kairi’s and Riku’s. 

And then he was standing on solid ground, in silence. He blinked his eyes open.

“Where are we?” he asked.

Riku slumped against him. “Earth. I don’t know where,” he mumbled. “It’s hard to be specific, just… wherever the line was thinnest.”

“How did you do that?” Kairi said.

“Hive magic,” Riku explained vaguely. “Takes a lot to do it. I… I don’t want to do it anymore.”

“You’re safe now,” Sora said softly. “It’s okay--”

“I mean, I’m really not,” Riku said dryly. “I’m definitely not okay, and we’re absolutely not safe.” He shoved himself upright. Shadows leaked from his eyes and crept through the Awoken shimmer of his skin. “We have to find him and kill him, permanently, before he can do any more damage. Before he can take anyone else.”

“You’re a Guardian,” Sora said. “How did he…”

“It’s not… like Taking, like Oryx.” Riku flexed his fingers until wisps of purple void swirled around them. “I don’t know how to explain it. It… he just… took my Light. Shoved it in that crystal. And… I couldn’t do anything. It’s… it’s hard to…” He pressed the heel of his hand to his face. “My head hurts.”

Kairi touched his shoulder gently. “We need to get you back to the Tower,” she murmured. “Someone will know what to do. Ikora… or Eris…”

Riku nodded. He stared at them for a second before bursting out an exhausted laugh and pulling both of them in close. “I’m so happy you guys found me,” he said. His hoarse voice cracked. “You’re both so stupid for coming after me without knowing what you were getting into, and don’t you ever do that again, but thank you.”

Sora squeezed him back tightly as his Ghost confirmed their ships moving in from orbit. “We’ll always come to help you, Riku,” he promised. “We’re friends. We’re your fireteam. We’ll never leave you behind.”

Riku rubbed at his eyes as he pulled back. He frowned at the shadows that dissipated from his hand. “Do you think Eris has another blindfold she can loan me?” he joked weakly.

“We’ll find a way to help you,” Kairi said, taking his hand in both of hers. “And then we’ll stop Xehanort before any more Guardians get their Light trapped for good.”

Riku nodded, looking worried, solemn. “We definitely need to get a warning out, too. I’m not sure where he goes, or what he does, or… maybe I do know.” He frowned. “It’s weird. It’s…”

“Easy,” Sora warned. “We’ll get home, and you’ll need to rest, and then Ikora and Eris can help. Don’t try to do anything yet. We’re here for you, Riku.”

**Author's Note:**

> my tumblr: lesbianeliksni  
> bb's KH tumblr: sorikaimutual (main: thebookwormbakery)


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